1. Technical Field
The present invention relates to a head which ejects a liquid, and a liquid ejecting apparatus which is provided with the head, and particularly relates to an ink jet recording head and an ink jet type recoding apparatus which eject ink as the liquid.
2. Related Art
A piezo ink jet system is an on-demand type ink jet printing system which discharges a liquid droplet by deforming a piezo element through the applying of a voltage to the piezo element (JIS Z8123-1: 2013).
A permanent head is a machine portion or an electrical portion of a printer main body which continuously or intermittently generates a liquid droplet of ink (JIS Z8123-1: 2013).
The permanent head (hereinafter, referred to as a “head”) which is used in the piezo ink jet system is provided with a channel formation substrate on which a pressure generating chamber, which communicates with a nozzle for ejecting a liquid droplet is formed, a piezo element which is provided on one surface side of the channel formation substrate, and a driving circuit board in which a driving circuit which is bonded onto the channel formation substrate so as to be close to the piezo element and drives the piezo element is provided. The permanent head ejects the liquid droplet from the nozzle by driving the piezo element by the driving circuit and applying a pressure change to the liquid in the pressure generating chamber.
As the head described above, a head which is configured such that a driving circuit and a bump are provided on a surface of a driving circuit board facing a channel formation substrate, and the driving circuit and the piezo element are electrically connected to each other via the bump has been proposed (for example, refer to JP-A-2014-51008). The driving circuit board and the channel formation substrate are bonded to each other by using an adhesive which is provided in the vicinity of the bump. The bump and the adhesive have a constant height, and are used to form a holding portion which is a space for accommodating the driving circuit and the piezo element between the driving circuit board and the channel formation substrate.
The driving circuit is disposed to face the piezo element which is accommodated in the holding portion (a so-called face down disposition). Since the driving circuit is accommodated in the holding portion, an input portion for inputting signals from an external control circuit to the driving circuit is provided on the outside of the holding portion on the driving circuit board. With such an input portion being provided on the driving circuit board, it is possible to transfer a signal to the driving circuit in the holding portion.
However, since the driving circuit board is required to secure not only an area for the driving circuit but also an area for the input unit, the size of the driving circuit board becomes enlarged. In addition, if the driving circuit board is enlarged, the number of boards obtained from one raw material is decreased, and thus cost is increased.
In addition, such a problem exists in not only a head for ejecting ink, but also a head for ejecting liquid droplets other than the ink.